Heat oil in a large saucepan over medium heat. Add the leek, onion, garlic and thyme and cook, stirring, for 1 minute or until the onion and leek softens slightly.
Increase heat to high. Add the zucchini, potato, stock and bring to the boil. Cook, stirring occasionally, for 10 minutes or until the potato is tender. Remove from heat and cool for 5 minutes.
Blend together in a food processor or blender until smooth. Return soup to the heat to warm through.
Season with salt and pepper. Serve with cream or parmesan cheese (or both!) and with crusty bread.
This can be frozen in portions depending on what size meal you would like. For adults I would store it in a Sinchies 500ml reusable pouches